I have copied two posts of mine from the Chrysler Town & Country Forum in a hope to get an answer here:
Could anyone tell me if the "Oil Change Required" indicator is tied to a timer or a sensor? I suspect it is a timer based on mileage rather than a sensor. I have spectrometal analysis conducted for my truck's diesel engine, transmission, transfer case, coolant, etc. I haven't had this performed for the minivan as it seemed unnecessary as it is so inexpensive to get the oil changed in a passenger vehicle compared to a commercial truck. If it is a sensor, could you tell me what it measures? Particulate count/density, additive concentration, wear-metal density, viscosity change...
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...just because I see that I omitted this in the original post...

I know how to "reset" the indicator. It is covered in the Owner's Manual as well as in other online forums. I have reset the indicator before:
Key On, Engine Off
Depress throttle to floor 3 times within a 10 second window
Key Off

Just to be absolutely clear - I am trying to find out if this "Oil Life" indicator is a SENSOR or a TIMER and its associated unit of measure (i.e., SENSOR and a meaure of particulate density in ppm of soot/insoluables triggered at x.xx%, SENSOR and a measure of aluminum wear-metals in ppm triggered at xx, TIMER and a measure of mileage triggered at 2,500-miles, TIMER and a measure of months triggered at 3 months, etc.).

Thanks!
Jonathan

 

its all in your owners manual page 230

 

Thank you for your response but I guess I should have pointed out that I have referred to the Owner's Manual already.

Page 230 is for the Tire Pressure Monitoring System.
Page 238 does describe the "CHAngE OIL" notification in the Odometer Display Area.

It ambiguously describes that "The engine oil change indicator system is duty cycle-based, which means the engine oil change interval may fluctuate dependent upon your personal driving style."

I don't know how the "duty cycle-based" analysis is determined. Is it a TIMER or a SENSOR or a combination of both or neither and something else entirely?

I'm looking for a more precise and specific answer after having reviewed the Owner's Manual and found it to be less than fully descriptive.

Thanks.

Jonathan

 

its right here in this paragraph page 230

CHAngE OIL
Your vehicle is equipped with an engine oil change
indicator system. The “Change Oil” message will flash in
the instrument cluster odometer for approximately 12
seconds after a single chime has sounded to indicate the
next scheduled oil change interval. The engine oil change
indicator system is duty cycle-based, which means the
engine oil change interval may fluctuate dependent upon
your personal driving style.
Unless reset, this message will continue to display each
time you turn the ignition switch to the ON/RUN
position. To turn off the message temporarily, press and
release the Trip Odometer button on the instrument
cluster. To reset the oil change indicator system (after
performing the scheduled maintenance) refer to the following
procedure.

 

Okay. I am not trying to sound flip so I apologize if my note was interpreted negatively. That is absolutely not my intent. I am trying to get an answer to the question I posed in regards to the system in use on the 2008 Chrysler Town & Country Limited minivan for clarity in its determination of "duty cycle-based" oil monitoring.

I am an Aerospace Engineer. I am in the US Army Corps of Engineers. I do understand there is a system in the vehicle that is providing an alert for some threshold having been met to prompt an oil change. I ordinarily perform my own preventative maintenance on my vehicles. I have been exposed to the Army Oil Analysis Program for over 16 years and use spectrometal analysis to monitor the condition of the fluids in my diesel engine powered truck. I don't say this to self-endorse any qualification that I may or may not have, just to provide assurance that I will do my best to understand a fully technical description - that is, after all, what I am seeking.

"Duty cycle-based" does not answer if the method of determining the wear on the oil is from a sensor or a timer. I should have posted in the first message that I both have the Owner's Manual and had read the description provided on page 238 and found it to be less than fully informative. I am of course interested in properly maintaining the vehicle but I am equally interested in how the vehicle is helping me to keep it properly maintained. That is what prompts me to ask what is being measured specifically in the "duty cycle-based" determination. I consider myself an automotive enthusiast so it seems logical as an engineer to question "how" something works - the system-based description.

If that answer can't be provided then that at least is an answer and not a deflection to the Owner's Manual - which is where I started and found unsuitable.

Please forgive me for going on about this. I do greatly appreciate that I am not an expert on the Chrysler minivan. It is a technological improvement over the 2005 I used to have. If it is a trade secret it would surprise me but I thought the Chrysler Forum was the best first place to seek a description of the method of measurement.

There are many posts regarding the reset procedure when using any internet search engine. Several of these posts note the high frequency of the "Oil Change Required" message beginning at 2,500-miles. I know there are folks who drive their minivans overly aggressive with great strain upon the engine-transmission but I am not one of those individuals. I am going to change the oil. I am going to get a spectrometal analysis. If the car is sampling the oil by a sensor and it is alerting based on a concentration of a substance it would be a fact I am interested in knowing as well.

Thank you. Again, please don't misconstrue my post as negative. I am seeking expert input.

Jonathan

 

its basically software that knows the engines how its run and based off how u drive the longevity of the oil lasts that is the duty cycle. Kinda like u know how many calories U burn if U jog,walk, and do certain activities. Here is from the Chrysler web site the tests use the best answer there is to it.


The change oil indicator gives an indication to the vehicle operator when a duty-cycle algorithm contained within the software of the Powertrain Control Module (PCM) (also known as the Engine Control Module/ECM) determines that a recommended oil change interval has been attained. This indicator is controlled by the instrument cluster logic circuit based upon cluster programming and electronic messages received over the Controller Area Network (CAN) data bus from the PCM.

The change oil indicator function of the odometer or Electronic Vehicle Information Center (EVIC) Vacuum Fluorescent Display (VFD) unit is completely controlled by the instrument cluster logic circuit, and that logic will only allow this indicator to operate when the instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the odometer or EVIC VFD change oil indication will always be OFF when the ignition switch is in any position except ON or START. The instrument cluster will turn ON the change oil indicator for the following reasons:

Change Oil Indicator Lamp-On Message - Each time the ignition switch is turned to the ON position and the cluster receives an electronic change oil indicator lamp-ON message from the PCM indicating that a duty-cycle based recommended oil change interval has been attained, the change oil indicator will be illuminated for about three seconds, until the trip odometer reset switch button or an EVIC steering wheel switch button is depressed, or until the ignition switch is turned to the OFF position, whichever occurs first.
Change Oil Indicator Reset Procedure - Once an engine oil change has been completed, the PCM duty cycle counters can be reset using the following procedure. Turn the ignition switch to the ON position, but DO NOT start the engine. Slowly depress and release the accelerator pedal fully three times within ten seconds. Turn the ignition switch to the OFF position. If the change oil indicator illuminates the next time the engine is started, repeat this procedure.
The PCM continually monitors numerous sensor inputs to determine the duty-cycles to which the engine is being subjected. A pre-programmed algorithm within the PCM then determines when to send the proper lamp-ON or lamp-OFF message to the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN).

For proper diagnosis of the change oil indicator, the PCM, the EMIC, the CAN data bus or the electronic communication related to change oil indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information

 

Thank you. It seems that it is basically a timer with input from several of the other onboard electronic sensors based on driving habits (i.e., jack-rabbit starts measured by throttle position over time, short trips not attaining optimal operating temperature measured by the engine and oil coolant temperature sending units, etc. would contribute to lower oil life computed through an algorithm...x% degradation from regularly expected life of the recommended grade oil of the proper viscosity). So there are sensors involved but not a sensor in the oil system - that would be quite a remarkable sensor! Thank you for the answer.

Jonathan

 

Yes, preprogrammed fuzzy logic